Manufacture of alpha composite sheet



Sept. 13, 1932. w. R. COLLINGS MANUFACTURE OF A COMPOSITE SHEET FiledJune 5, 1929 ON N INVENTOR BY 14) I ATTORNEY Patented Sept. 13, 1932UNITED STATES PATENT OFFICE WILLIAM R. COLLINGS, OF MIDLAND, MICHIGAN,ASSIGNOR TO THE DOW CHEMICAL COMPANY OF MIDLAND, MICHIGAN,

A CORPORATION OF MICHIGAN MANUFACTURE OF A. COMPOSITE SHEET Applicationfiled June a,

, The present invention relates to a method of forming a composite sheetand in particular to a method of treating or moistening the materialduring its manufacture so that a more intimate contact may be hadbetween its components.

Heretofore in the manufacture of a composite sheet the general practicewhere making a two ply reenforced sheet has been to coat the adjacentfaces of the two sheets with adhesive and then to pass them withreenforcement therebetween through squeezing or sealing rolls, the samemethod being applied where the composite sheet contains more than twoplies. Such practice, however, I have found does not permit the paperand adhesive to give sufiiciently to allow the adhesive to form as gooda bond between the components of the sheet as may be obtained where thesheet is treated or moistened according to my improved process.

The principal object of my invention is accordingly to provide a methodof forming a composite sheet to permit a better union of the componentsthereof. Other objects and advantages will appear as the descriptionproceeds.

To the accomplishment of the foregoing and related ends the invention,then, consists of the method hereinafter fully, described andparticularly pointed out in the claims, the annexed drawing and thefollowing description setting forth in detail several modes of carryingout the invention, such disclosed modes illustrating, however, butseveral of various ways in which the invention maybe use In said annexeddrawing Fig. 1 is a diagrammatic side view of one preferred type ofapparatus for carrying out the present invention; Fig. 2 illustrates onetype of reinforced sheet produced by the machine diagrammatically shownin Fig. 1.

In general, my improved process includes temporarily softening at leastone of the paper sheets of a composite sheet prior to passing saidcomposite sheet through the final pair of squeezing or sealing rolls.For instance, where forming a composite sheet-uti 50,1izing two sheetsof crepe paper, 12 pound 1929. Serial No. 368,190.

sheet, the strands of yarn 'n each ply being placed approximatelyparallel and about of an inch apart. A square or diamond shaped mesh isthereby formed with said yarn. ing been brought together with thereenforcing therebetween, are passed through a pair of squeezing orsealing rolls that squeeze the adhesive around the reenforcing yarn andinto the surface of the paper.

with adhesive coated faces The sheets coated with adhesive, hav-However,

prior to passing the composite sheet through the squeezing rolls Isubject at least one sheet of the paper thereof to a softening processas by blowing wet steam onto the back or un- I coated side of such sheetso as to soften the paper slightly which enables the squeezing rolls todepress the so softened paper through the openings between thereenforcing yarns intoa very intimate adhesive contact with tlie yIarnand the sheet on the other side there- 0 and formed composite sheet isused for mak-' ing bags, such for instance as used for packaging flakecalcium chloride in pound lots, the so made bag will withstand in somecases twice as many drops of 40 inches each than will a similar bag madeout of the same materials but not so treated before the final sealingstep. This improved characteristic is due to the better union of thepaper sheets rial. At least one of the squeezing rolls may be of a softresilient character or a resilient sheet may be run between it and thesoftened paper. Such facilities will aid in pressing the softened sheetinto intimate contact with have found that where'my so treated V witheach other and the reenforcing matethe opposite sheet and with the yarnor other I reenforcement.

' ried thereby.

Referring more particularly to the drawing, Fig. 1 shows in diagrammaticmanner one of many combinations of apparatus suitable for carrying outthe present invention. In operating this apparatus a sheet 1 is drawnfrom supply roll 2 supported in any' suitable manner as by a standard 3.The sheet leaving roll 2 passes over an idler roll f and thence aroundroll 5 Where a coat of adhesive is applied on one side thereof. Thesheet then passes between two' series of rollers 10 and 11 wherereinforcing yarn strands 19 are placed on the adhesive-coated face ofthe sheet. A second sheet 12 is then placed over the reinforcing strandscarried on the adhesive-coated face of sheet 1 and the whole is passedbetween squeeze rollers 13 and 14 where the sheet is consolidated intofinal form, following which it may be delivered directly to a point ofuse or rolled up as shown. The application of adhesive to one faceofsheet 1 can be convenientlytaken care of as follows :Roll 7 dips in abath of adhesive 8 contained in trough 901' the like, rotation of roller7 carrying a film of adhesive to roll 6, the relatively close spacing ofroll 6 to roll 7 determining the thickness of the adhesive layer carriedon the face of roll 6 into contact with sheet ,1 passing around roll 5.Where the adhesive is of an asphalt base type, rollers 5, 6, and 7, aswell as trough 9, are steam heated, the rollers being made hollow withsteam entrance through the trunnions 28, 29, and 30 thereof. Theadhesive-containing trough 9 is likewise heated by means of a steamacket15 or its equivalent through connection 31. The adhesive on sheet 1after leaving roll 5 is either dried, or cooled in the case of hotasphalt or the like, so that when it reaches rollers 10 and 11 anytendency. to stick to rollers 11 will be reduced to a negligible pointalthough it is preferable to have a slight amount of stickiness left sothat when the yarn strands are placed thereon they will be held in placeand car- While the .yarn strands or other reinforcing material can beapplied to the adhesive-coated face of sheet 1 in any 1 convenientmanner, I prefer to apply same in the form of strands which arediagonally laid in two plies one over the other by means of a mechanismof the type diagrammatically shown. This mechanism functions as follows:-Carriage 16 is equipped with rollers 17 on each end thereof, suchrollers engag ing tracks 18 in such manner that the carriage can bemoved backward and forward j across sheet 1 and in a path directlytheref above and stopping just short of reaching the respective edgesthereof. The mechanism .for continuously bringing the carriage 16 backand forth across the face of sheet 1 in uniform manner may be of anyconventional type (not shown). Yarn strands 19 used for reinforcing thecomposite sheet may be drawn from any suitable source of supply, such,for instance, as spools 20. A yarn strand 19 after leaving the spool 20passes through a guide eyelet 21 at the upper edge of carriage 1 6 andthence to another guide eyelet 22 which delivers the yarn strand underroll 11 which extends entirely across'the sheet and presses the yarnstrand onto the adhesivecoated face of sheet 1. 'By making carriage 16approximately twice as long (end eyelet to end eyelet) as the sheetbeing reinforced is wide and having it move across the sheet at the samerate of speed that the sheet is travelling lengthwise, the yarn will belaid at an angle of approximately 45 from the edge of the sheet, in twolayers, one above the other in unwoven manner, as is shown in Fig. 2.Sheet 12 which is brought into contact with the adhesive-coated andreinforced matically or hand adjusted to the desired consolidationpressure. At least one of the squeeze rolls, for instance 13, may bedesirably covered with a resilient coating such as a rubber facing. Byoperating in this manner, I have found that although acomposite sheetcan be made, it is not as strong and well bonded together as isdesirable since the paper sheets have a certain amount of resiliencywhich causes them to pull apart slightly after leaving the squeezerolls, the particular pointof most difiicultyoccurring at thereinforcing yarns. This difliculty I have found can be substantiallyeliminated by the application of a small amount of moistening agent,specifically a fewpcr cent, to the back of at least one of theadhesivecoated sheets prior to applying the final squeezing orconsolidation pressure to the reenforced composite sheet. For instance,wet

. squeeze rollers 13 and 14 which may be autosteam may be blown onto theback of sheet 1 by means of nozzles 24 mounted on the valve controlledsteam pipe 25. The amount of steam required is only enough to soften orwhen it passes between squeeze rollers 13 and 14 its resiliency willhave been reduced just to a' point Where it will not pull away from the.opposite sheet after being consolidated. If desired, the back orunadhesive-coated face of sheet 12 can be treated in like manner byslightly dampen the back of sheet 1 so that tact with the face ofsqueeze roll 13. Roll 13 under such conditions will take up a thin filmof water and transfer it to sheet 1 so as to very slightly moisten samein equivalent manner to steaming. In some cases it may be desirable toboth steam and sponge the back of at least one of the sheets, and incertain combinations the moistening could be advisedly done by one whilethe other acted as a standby for emergency use.

IVhile I have described my invention employing steam to moisten the backof one sheet after applying adhesive but before passing through thesqueezing rolls I do not wish to be limited to that mode only, as it isobvious that both sheets might be so moistened and in case an adhesiveof the glue type should be used, moistening might even take place beforethe application of adhesive. In some cases, however, applying moistureto on sheet only would be preferable since such procedure would allowsuch sheet to give and form a satisfactory union between the componentsof the composite sheet without causing any or excessive depressions onthe opposite side of the composite sheet thereby leaving that side flatand better adapted for applying label or printed matter. In some casesonly one of the sheets will have adhesive applied thereto in which caseif the adhesive is waterproof or semi-waterproof the back of theadhesive coated sheet will be moistened before sealing. The compositesheet may also contain more than two paper sheets and still retain theadvantages of my invention by moistening the back of at least one of theoutside sheets, preferably one adjacent to the reenforcement, prior topassing through the squeezing rolls. Such moistening in any case may bedone by merely spraying, sponging, steaming or otherwise applying 'waterdirectly to the sheet, steaming in some cases being preferable due toits furnishing a certain amount of heat simultaneously with themoistening, such heat tending to slightly soften the adhesive and thusfacilitate the formation of a better union between the components of thecomposite sheet. In any case the amount of moistening agent,specifically water, used to temporarily soften at least one of thesheets is very small, in fact increasing the moisture content of drypaper which is normally 3 to 6 per cent, up to an approximate total offrom 8 to 12 per cent is all that is necessary for satisfactoryoperation.

While I have further described my invention as applied to preparing acomposite sheet utilizing, as reenforcement, two layers of diagonallylaid parallel strands of yarn crossing each other, I do not wish to belimited to that construction since it will be obvious to anyone skilledin the art that the advantages of moistening may be attained where usingother types of reenforcement such as fibres, burlap, scrim, cheeseclothor the like and that in some cases it may be even of advantage where noreenforcement is used. While in my so prepared composite sheet I preferto use crinkled paper and asphalt adhesive having a penetration factorof from 30 to 40 I do not wish to be limited to them, since it islikewise obvious that other papers and adhesives may be used inequivalent manner depending upon the service required and other factors.

Other modes of applying the principle of my ilwention may be employedinstead of those explained, change being made as regards the processherein disclosed, provided the step or steps stated by any of thefollow-- ing claims or the equivalent of such stated step or steps beemployed. I therefore particularly point out and distinctly claim as myinvention 1.. In a method of the character described, the steps whichconsist in assembling a plurality of component sheets with reenforcementand adhesive thercbetween, temporarily rarily softening at least onecomponent thereof by treating the back of same with a low percentage ofwater prior to applying final pressure to consolidate the assembly.

2. In a method of the character described,

the steps which consist in assembling a plurality of component sheetswith reenforcement and adhesive therebetwcen and temposoftening at leastone of the component sheets by slightly dampening the back of same, andthen applying pressure to consolidate the assembly.

' 3. In the manufacture of a composite reinforced sheet, the step whichconsists in temporarily softening at least one component thereof with asmall amount of moistening agent prior to applying final pressure toconsolidate the composite sheet.

4. In the manufacture of a composite reinforced sheet, the step whichconsists in temporarily softening at least one of the component sheetsby applying a small amount of moistening agent to the back thereof priorto applying final pressure thereto.

5. In the manufacture of an adhesively assembled composite reinforcedsheet, the step which consists in steaming at least one of the componentsheets thereof to slightly dampen same prior to applying final pressureto the assembly.

6. Iirthe manufacture of a composite reinforced sheet, the step whichconsists in steaming the back of at least one of the adhesively coatedcomponent sheets thereof prior to applying final pressure to theassembly.

7. In the manufacture of a composite reinforced sheet, the step whichconsists in temporarily softening at least one of the component papersheets thereof with a small amount of moistening agent prior to finalassembly.

8. In a method of finishing a composite sheet composed of a plurality oflayersof tcomponent sheets with reenforcement and adhesive therebetween,the step which consists in. temporarily softening atleast one ofadhesive-coated component sheets by slightly 'moistening the backthereof before applying final .pressureto the assembly.

9. In the. manufacture of a composite sheet,

thesteps wl'iich consist in applying adhesive to adjacent faces of twocomponent sheets,

. temporarily softening at least one such sheet by applying a few percent of moisture to the back thereof, inserting reenforcing material andsubjecting the so assembled composite sheet to pressure.

10. In the manufacture of a composite sheet, the steps which consist inapplying adhesive to adjacent faces of two sheets, steaming the back ofat least one such sheet, in-

' sorting reenforcingmaterial and subjecting the so assembled compositesheet to pressure.

11. In the manufacture of a composite sheet, the steps which consist inapplying an asphaltic adhesive to adjacent sides of two sheets,softening at least one such sheet by applying a small amount of moistureto the back thereof, inserting reenforcing material and passing the soassembled composite sheet through pressure sealing means.

12. In the manufacture of a composite sheet, the steps which consist inapplying asplialtic adhesive having a penetration factor ofapproximately 35 to adjacent sides of two paper sheets, steaming theback of at least one such sheet, inserting 'reenforcing material andpassing the so assembled composite sheet through pressure sealing means.

13. In the manufacture of a composite sheet, the steps which consist inapplying adhesive to at least one face of two or more sheets of paper,moistening the back of at least one of the outer adhesive-coated sheetswith a small amount of Water, inserting reenforcing material and passingthe so formed -composite sheet through pressure sealing means.

Signed by me this 29th day of May, 1929.

WILLIAM R. 'ooLLINGs.

CERTIFIEATE 0F .GQRREGTEQN,

Patent No. 1,877,270. a September 13, 1932.,

WILLIAM R. CQLLINGS.

it is hereby certified that error appears in the printed specificationoi the above numbered patent requiring correction as follows: Page 2,line 10, for "on" read "to"; page 3, line 2L, for "on" read "one"; line89, claim 31, strike out the word "rarily"; and line 96, claim 2, for"tempo read "temporarily";

page 4, line 4, claim 8, after "oi" insert the words"the said"; and thatthe said Letters Patent should be read with these corrections thereinthat the same may eoniorm to the record oi the case in the Patentfiitice,

Signed anti sealed this 27th day of December A. D. 1932.

hi, 3 M00112, (Seal) Acting Commissioner of Patents,

